This invention concerns apparatus for scavenging anesthetic gas from around a mask.
Fischer, Jr. et al. (U.S. Pat. No. 4,265,239; 1981) describes a mask having an exhaust assembly for removing exhaled gases. This assembly also has a peripheral exhaust chamber for scavenging gases leaking from the mask.
Brown (U.S. Pat. No. 4,015,598; 1977) describes an anesthetic mask for collecting gases exhaled by a patient and gases leaking from the mask. The mask has an inner shell connected by a pressure relief valve to an outer shell. Gases in the outer shell are removed by an exhaust pump. The outer shell is open at its lower surface to scavenge gases which leak from the mask.
Czajka (U.S. Pat. No. 4,219,020; 1980) describes a scavenging attachment which replaces the exhalation valve of a conventional face mask. The attachment has a floating disc check valve connected to a generally concave inverted saucer-shaped vacuum chamber. Gas leaking around the periphery of the mask is scavenged by a vacuum connected to this chamber. Exhaled gases are also removed by a vacuum system connected to this chamber.
Gedeon et al. (U.S. Pat. No. 4,538,605; 1985) describe an apparatus having a pressure activated valve which regulates the operation of a suction device on a gas mask. When the valve is turned on all gas entering the mask is sucked away by the device.
Hoenig (U.S. Pat. No. 4,527,558; 1985) describes a scavenging system in which all gases exhaled by a patient are collected in a manifold and then sucked away by a vacuum system.
Fischer (U.S. Pat. No. 4,248,218; 1981) describes an apparatus for administering gas via nasal cannulae. These cannulae are surrounded by a mask connected to a vacuum system which removes exhaled gases. Gases exhaled through the mouth are scavenged through this mask via apertures in its base.